Prefabricated cast concrete panels are commonly used in constructing buildings and the like. Such panels may be fabricated at a manufacturing facility utilizing well-known continuous casting processes and shipped to the building site for installation.
Referring now to the drawings, FIG. 1 depicts a commonly-used, hollow cast concrete panel member, generally designated by the numeral 10. The panel member is fabricated by first horizontally casting a bottom panel section 12 at a first assembly station. Next, while the bottom panel section is still uncured, vertical spaced-apart web sections 14 are continuously cast over the bottom panel section 12.
Such casting is typically accomplished using slip forms which define the web sections. Simultaneously, gravel is poured into the regions between the slip forms where voids 20 in the panel are to be formed and over the bottom panel section 12. Finally, the concrete is poured over the webs and gravel to form a top panel section 16. The gravel serves to support the top panel section 16 until the section has cured. Curing is typically accomplished utilizing steam or other methods. The continuously cast panel member is then cut to the desired length.
Inasmuch as the panel member is quite heavy, it is necessary to use cranes and the like for maneuvering and positioning the panel. Preferably, anchor assemblies are inserted into the panel members during the casting process. The embedded anchor assemblies are then used for purposes of tilting up or otherwise hoisting the panel member.
The prior art anchor assemblies are fabricated from metal reinforcing bars (rebar). The assemblies include a pair of spaced-apart curved rod members 18 which are formed from a length of rebar which is bent 180 degrees to form a U-shaped member which is typically approximately two feet in length. The curved rod members 18 are connected together by at least three transverse cross-rod members 21 which are welded to the lower half of the curved rod members 18. The curved rod members, which are supported in a vertical position by the cross-rod members, must be spaced apart a distance so as to coincide with the spacing of the web sections 14 to be subsequently cast.
The prior art anchor assembly is embedded in the panel member during the casting process. First, the bottom panel section 12 is cast, as previously described. Next, the anchor assembly is positioned over the bottom panel section, with the lower portion of the curved rod members and the cross-rod members providing support on the surface of the uncured concrete. The assembly is positioned such that the vertical curved rod members 18 will coincide with the locations where the web sections 14 will be cast, as previously described. Next, the slip forms are positioned over the bottom panel section 12 and gravel is deposited where the voids 20 in the panel member are to be located. The web sections are then cast, followed by the casting of the top panel section 16.
Once the panel member 10 has cured, the member is cut to the desired length. The cut will be approximately 1/2 inch from the bent ends of the curve rod members 18. Preferably, some means of marking is used during the casting process so that the imbedded rod members can be located. A chisel or other chipping tool is then used to remove a portion of the proximate ends of the web sections 14 so as to expose the curved portion of the two rod members 18.
The proximate ends of the exposed portion of the curved rod members are recessed within the panel member 10 by approximately 1/2 inch so as not to interfere with the installation of the panel member in a building. It is not possible to apply a hoisting shackle directly through the loop formed in the curved rod member 18 since the shackle will have a tendency to damage the panel member in the area of the loop. Accordingly, a strongback, generally designated by the numeral 22, must be used. Strongback 22, which has an L-shaped cross-section, is fabricated from heavy guage metal.
The strongback is secured to the curved rod members 18 using a pair of hooked members 26. The hooked members have a curved section which extends through the loop formed in rods 18, and a threaded section which extends through corresponding openings 24 formed in the face of the strongback 22. Nuts 28 are then positioned over the threaded ends of hooked members 26 and tightened thereby rigidly securing the strongback to the anchor assembly embedded in the panel member. The strongback is provided with a pair of metal shackles 30 which are then used in conjunction with a hoisting shackle for lifting the panel member. Once the panel member is in place, nuts 28 are loosened and the strongback is removed.
The previously-described prior art anchor assembly possesses several shortcomings. First, it is necessary to match the spacing of the curved rod members 18 with the position of the web sections 14. Thus, flexibility is significantly reduced with respect to the construction of the anchor assembly and with respect to the positioning of the webs 14 of the panel.
In addition, the relatively large size of the anchor assembly and the limitations on the position of the assembly frequently interfere with the placement of other types of embedded inserts and tension cables. Perhaps most importantly, the prior art anchor assembly requires the use of a strongback. Accordingly, a substantial amount of time and labor is required to install and remove the strongback.
The subject invention overcomes the above-described limitations of the prior art anchor assemblies. The subject invention allows the panel webs 14 to be spaced wherever desired, and does not significantly interfere with the positioning of other types of inserts. Furthermore, a lifting shackle may be attached directly to the subject anchor assembly, thereby obviating the requirement that a strongback be used. These and other advantages of the subject invention will become apparent to those skilled in the art upon a reading of the following Best Mode of Carrying Out the Invention together with the drawings.